Germ line mutations causing paediatric cancer predisposition syndromes (PCPSs) are more common than previously anticipated and are now recognised as a significant contributor to the incidence of childhood cancer. Advances in and increased clinical application of next-generation sequencing technologies have led to a rise in paediatric patients undergoing whole genome sequencing (WGS). This review focuses on the potential syndromes/diagnoses, which WGS may reveal in patients with childhood cancers, and highlights the clinical and psychosocial impact of PCPSs.